Jaafar, H.Z.E., Ibrahim, M.H. and Karimi, E. 2012. Phenolics and flavonoids compounds, phenylanine ammonia lyase and antioxidant activity responses to elevated CO2 in Labisia pumila (Myrisinaceae). Molecules 17: 6331-6347.
The authors write that "plant antioxidants have been a focus of attention in recent years due to the health preservation functions of these components that can help reduce the threat of chronic diseases such as cancer, diabetes and hypertension," which benefits are "attributed to the high scavenging activity of antioxidants towards free radicals that are usually associated with these diseases (Byers and Guerrero, 1995)." Among this group of plant compounds are phenolic acids and flavonoids, both of which exhibit, as they describe it, "high anti-inflammatory and anti-carcinogenic activities (Heijnen et al., 2001; Chun et al., 2003)." In addition, they note that phenolics and flavonoids can function as reducing agents, free radical scavengers and quenchers of singlet oxygen formation (Chan et al., 2008)," and they state that many of the components of polyphenols have been proven to have significant roles in "curing cancer and other human ailments (Harborne and Williams, 2000)."
What was done
Jaafar et al. conducted a split plot 3 x 3 experiment that was designed to examine the impact of 15 weeks of exposure to three concentrations of CO2 (400, 800 and 1200 ppm) on the phenolic and flavonoid compound profiles - as well as the antioxidant activities - of three varieties (alata, pumila and lanceolata) of Labisia pumila Benth. or kacip fatimah as it is commonly known throughout Southeast Asia, which they describe as "a sub-herbaceous plant with creeping stems from the family Myrsinaceae that is found widespread in Indochina and throughout the Malaysian forest," and which has historically been used to help maintain a healthy female reproductive system.
What was learned
Among a wide variety of findings, the three Malaysian researchers report that when exposed to elevated CO2 (1200 ppm), "gallic acid increased tremendously, especially in var. alata and pumila (101-111%), whilst a large quercetin increase was noted in var. lanceolata (260%), followed closely by alata (201%)." They also indicate that "caffeic acid was enhanced tremendously in var. alata (338-1100%) and pumila (298-433%)," while "rutin continued to increase by 262% after CO2 enrichment." In addition, they found that naringenin was enhanced by 1100% in var. pumila. Last of all, they report that "the increase in production of plant secondary metabolites in L. pumila was followed by enhancement of the antioxidant activity under exposure of elevated CO2."
What it means
With respect to the implications of their several findings, Jaafar et al. say they point to "the possible improvement of [the] health-promoting quality of Malaysian L. pumila under high CO2 enrichment conditions."
Byers, T. and Guerrero, N. 1995. Epidemilogic evidence for vitamin C and vitamin E in cancer prevention. American Journal of Clinical Nutrition 62: 1385-1392.
Chan, E.W.C., Lim, Y.Y., Wong, L.F., Lianto, F.S., Wong, S.K., Lim, K.K., Joe, C.E. and Lim, T.Y. 2008. Antioxidant and tyrosinase inhibition properties of leaves and rhizomes of ginger species. Food Chemistry 109: 477-483.
Chun, O.K., Kim, D.O. and Lee, C.Y 2003. Superoxide radical scavenging activity of the major polyphenols in fresh plums. Journal of Agricultural and Food Chemistry 51: 8067-8072.
Harborne, J.B. and Williams, C.A. 2000. Advances in flavonoid research science. Phytochemistry 55: 481-504.
Heijnen, C.G., Haenen, G.R., Vanacker, F.A., Vijgh, W.J. and Bast, A. 2001. Flavonoids as peroxynitrite scavengers: the role of the hydroxyl groups. Toxicology In Vitro 15: 3-6.Reviewed 12 December 2012